Theme development Instructions
http://code.tutsplus.com/articles/magento-theme-development-an-introduction--cms-21036
Magento Theme Development: Layout Files
http://code.tutsplus.com/articles/magento-theme-development-layout-files--cms-21037
Magento Theme Development: Template Files
http://code.tutsplus.com/articles/magento-theme-development-template-files--cms-21040
Frequently Used Functions in Magento Development
http://code.tutsplus.com/articles/frequently-used-functions-in-magento-development--cms-22458?utm_source=Tuts+&utm_medium=website&utm_campaign=relatedtutorials&utm_content=sidebar&WT.mc_id=Tuts+_website_relatedtutorials_sidebar
Custom Block Development in Magento
http://code.tutsplus.com/tutorials/custom-block-development-in-magento--cms-23104
Create a Custom Payment Method Module in Magento: Part One
http://code.tutsplus.com/tutorials/create-a-custom-payment-method-module-in-magento-part-one--cms-23464
